[clutter/msvc-support] (12 commits) ...Merge branch 'master' into msvc-support

[Chun-wei Fan <fanchunwei src gnome org>]

Summary of changes:

  2022e4c... clutter-stage: Don't override the user's perspective matrix (*)
  3460094... clutter-stage: Allow a wider range of visible z values (*)
  a978961... paint-volumes: remove alignment constraint for completion (*)
  30eb3be... paint-volumes: avoid trashing is_static state (*)
  394512b... paint-volumes: remove alignment constraint for _set_origin (*)
  923b165... paint-volumes: fix unioning with empty volumes (*)
  e6c58b7... build: Replace AC_HELP_STRING with AS_HELP_STRING (*)
  4dc30c2... paint-volumes: avoid is_complete assert in _axis_align (*)
  e936b95... paint-volumes: remove is_axis_aligned assert for _union (*)
  cb39997... Remove usage of clutter_group_add() (*)
  daaa4c5... tests/cally: Remove last uses of clutter_group_add() (*)
  a1a2d54... Merge branch 'master' into msvc-support

(*) This commit already existed in another branch; no separate mail sent